OPC UA PubSub Sniffing concepts
From OPC Labs Knowledge Base
Introduction
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Capture types
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Individual capture types
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Capture type groupings
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Terminal and non-terminal messages
The capture types denote either non-terminal or terminal messages.
- non-terminal message
- The message is further structured and can contain other non-terminal or terminal messages. Consequently, there can be more captures arising out of a single non-terminal message.
- terminal message
- The message is not structured (or cannot be parsed) to further sub-messages. No further capture will be emitted for the terminal message.
Parsed and unparsed messages
Normally, the capture mechanism parses all parts of the message that are necessary to collect the information provided by the message. When the message or its part is encrypted, it is possible that the capture mechanism will not be able to decrypt (and parse) the full message contents, but will still be able to determine the type of the message and some PubSub header information. Such case is indicated by one of the unparsed capture types.
For more information to when the unparsed capture types are used, see Security and sniffing.
Capture header
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Special cases
Transport message auto-transformations
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Security and sniffing
(TBD)
Data capture with sniffing
(TBD)
